JPS62178866A - Manufacture of heat insulator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat insulator used in refrigerators, frozen prefabricated products, and the like.

BACKGROUND OF THE INVENTION FIG. 3 shows a conventional heat insulator. The configuration of the conventional example will be explained below with reference to FIG.

In recent years, in order to improve the insulation performance of the insulation box, two
The use of a heat insulator with reduced pressure in the lower part is attracting attention. Powder such as perlite, honeycomb, foam, etc. are used as the core material of this heat insulating body.

For example, as shown in JP-A-57-133870, a proposal has been made to use a hard urethane foam having open cells as the core material. To explain this Japanese Patent Application Laid-Open No. 57-133870 with reference to FIG. 3, 1 is a heat insulating structure in which a hard urethane foam 2 having open cells is covered with a container 3 made of an airtight thin film, and the inside thereof is 0,001
The pressure is reduced to mm1Ht and it is sealed. The rigid urethane foam 2 is characterized in that a commercially available material with a closed cell ratio of about 80 to 90% is vacuum degassed under high temperature and high humidity to break the cell membrane and obtain open cells.

Problems to be Solved by the Invention However, in the conventional heat insulating structure 1 as described above, since the rigid urethane foam 2 manufactured by a general foaming method using a general-purpose resin raw material is used as a base material, a foam skeleton is formed. The solid heat conduction component conducted through is large, and the gas heat conduction component is sufficiently small 3,<.

Otherwise, it would be difficult to obtain a practically sufficient thermal insulation performance.In other words, in the conventional example, the bubble skeleton diameter was approximately 3Qo~
Since the thickness was 1000μm, the contribution of gas heat conduction would not be sufficiently reduced unless the pressure was reduced to 0,001 mmHS', and excellent heat insulation performance could not be obtained. However, from the point of view of production efficiency, the inside of the heat insulating structure 1 having a bubble skeleton diameter of about 300 to 1000 μm is 0.001 + m.
nH? 4, the exhaust conductance is very small and the evacuation time is very long, which in turn poses a major problem in mass productivity. Further 0.001 mmH
In the high vacuum region of S', it is susceptible to gas release from the material, and in particular, organic foams that tend to contain unreacted monomer components of low molecular weight have problems such as requiring a long evacuation time. .

In view of the above-mentioned problems, an object of the present invention is to provide a heat insulator that can be mass-produced by shortening the evacuation time by obtaining a hard urethane foam that exhibits excellent heat insulation performance even in a vacuum range that is easy to handle industrially. do.

Means to Solve the Problems The present invention aims to solve the above problems by using organic polyisocyanates, polyols, catalysts, and foam stabilizers.

A foaming agent, a cell communication agent, and a pyrolytic gas generating agent are mixed and foamed to form a rigid urethane foam with an open cell structure.
After this hard urethane foam is heat-treated until it reaches the decomposition temperature of the pyrolyzable gas generating agent, it is used as the core material of the heat insulator.

Effect: With the above structure, the cell membrane is torn during the foaming process and the open cell ratio becomes substantially 100%, and the cured hard urethane foam is heat-treated with a knife that reaches the decomposition temperature of the pyrolytic gas generating agent. , the pyrolytic gas generating agent dispersed in the cell skeleton is decomposed and gasified. For this reason, the bubble skeleton locally ruptures and becomes uneven and has an average thickness of 100 to 300 mm.Thermal resistance increases for heat conduction through the bubble skeleton, and the contribution of solid heat conduction is small. material can be obtained.

6 Beno Examples Hereinafter, the heat insulating body of the present invention will be explained with reference to Examples and FIGS. 1 and 2.

In the figure, 4 is a hard urethane foam manufactured in a urethane high-pressure foaming machine using the raw materials and blending parts shown in the table below, and is cut into predetermined sizes after being aged at room temperature.

In the table, polyol A is aromatic diamine 6, -7
This is a polyether polyol with a hydroxyl value of 4404 KOH/f obtained by addition polymerization of propylene oxide using ゜ as an initiator. The foam stabilizer is Tegostarb B-8404 manufactured by Goldschmidt ■, and the foaming agent is Freon R manufactured by Showa Denko ■.
-11. Catalyst A is D manufactured by Sankyo Air Products.
ABCO-TMR, catalyst B is dimethylethanolamine. The cell communication agent is calcium stearate manufactured by Nippon Oil & Fats Corporation. Organic polyincyanate A was obtained by reacting toluylene diisocyanate with trimethylpropane and diethylene glycol and had an amine equivalent weight of 16%.
0 polyisocyanate.

The thermal decomposition type gas generating agent is hydrazodicarbonamide manufactured by Sankyo Kasei ■. These raw materials are combined and foamed, and after hardening, the foam is cut into a predetermined size. After this, 180℃
heat treatment for about 2 hours to decompose the pyrolytic gas generating agent,
In addition, adsorbed water and unreacted monomers are evaporated to produce a metal-plastic laminate film 7A-, which is made of a laminate of an aluminum-deposited polyester film and a polyethylene film.

It is covered with a bag-like container 5 made of lume, and the inside is 0.01 mm thick.
The pressure was reduced to 0.1 mmHr, and the heat insulator 6 was obtained. The exhaust time at this time is
It was 5 minutes, 2 minutes. The thermal conductivity of the obtained heat insulator 6 is shown in the lower part of the table. Thermal conductivity is made by Vacuum Riko ■ - Mattc
The measurements were taken at an average temperature of 24°C.

As is clear from the table, it was found that the heat insulating body 6 of the present invention exhibits excellent heat insulating performance even at a pressure of 0.1 to 0.01 mmHf, which is easy to handle industrially. This is thought to be due to the fact that even though the heat transfer due to gas heat conduction increases, the heat transfer due to solid heat conduction decreases even more.

That is, in the hard urethane foam 4 with an open cell structure obtained by adding a pyrolytic gas generating agent, the pyrolytic gas generating agent is dispersed in the cell skeleton.
By applying heat treatment with a substance that reaches the decomposition temperature of the pyrolytic gas generating agent, the material is decomposed and gasified, resulting in local bursting of the cell skeleton, resulting in uneven thickness. Therefore, the solid thermal conductivity of heat transferred through the cell skeleton is reduced due to the newly generated thermal resistance, and the heat insulation performance can be improved. When selecting a pyrolytic gas generating agent, it is necessary to have a decomposition temperature that does not decompose depending on the reaction heat during foaming, and if it decomposes and gasifies during foaming, the foam will break violently and the normal foam will not be able to form. I can't get it. Further, the heating temperature condition does not change unless the temperature is such that the urethane foam 4 can be sufficiently decomposed in the atmosphere.

Effects of the Invention As is clear from the above description, the present invention provides the following effects. That is, the hard urethane foam with an open cell structure obtained by adding a pyrolytic gas generating agent has a temperature higher than the decomposition temperature of the pyrolytic gas generating agent after the pyrolytic gas generating agent dispersed in the cell skeleton. As a result of decomposition and gasification due to heat treatment, the bubble skeleton locally ruptures, resulting in uneven and uneven thickness. Therefore, the solid thermal conductivity for heat transfer through the cell skeleton is reduced due to the newly generated thermal resistance, and the heat insulation performance can be improved. Therefore, the vacuum heat insulating body 9 of the present invention has extremely excellent heat insulation performance even when the degree of vacuum is 0.1 to 0.01 mmHf. As a result, mass production can be carried out in a short time and with simple exhaust equipment, which has the advantage of contributing to a significant improvement in productivity.

[Brief explanation of drawings]

3 are sectional views of a conventional heat insulating structure. 4...Hard urethane foam, 5...
Container, 6...Insulator. Name of agent: Patent attorney Toshio Nakao and 1 other person 4-
Figure 1 to Legunfor, one stone's throw away

Claims (1)

[Claims] Organic polyisocyanates, polyols, catalysts, foam stabilizers,
Mixing a blowing agent, a cell communication agent, and a pyrolytic gas generating agent,
After foaming to form a rigid urethane foam with an open cell structure and heat-treating this rigid urethane foam to a temperature higher than the decomposition temperature of the pyrolytic gas generating agent, the foam is covered with a container made of a metal-plastic laminate film. A method for producing a heat insulator whose interior is sealed by reducing pressure.